1. Field of the Invention
The present invention particularly relates to a side airbag apparatus that is equipped to a vehicle such as an automobile and is deployed between a side door and an occupant for protecting the occupant.
2. Description of the Related Art
A side bag equipped to a vehicle, which is inflated by gas generated by burning gas propellant in an inflator and inflated to push an occupant, is typically provided with a vent hole for releasing the gas in order to avoid pushing too hard and thereby hurting the occupant. It is necessary to set the vent hole in such a position that the high-temperature gas generated in the inflator does not move toward the occupant. In conventional airbag apparatuses, as shown in FIG. 6, a vent hole 101 is usually disposed at a position in an airbag body 100, which is on the opposite side of an occupant H and on the lateral side to a vehicle body.
However, when the airbag body 100 is inflated, the lateral side to the vehicle body thereof adheres tightly to an inner wall portion of the vehicle compartment such as a door trim 102. Therefore, the vent hole is easily blocked and accordingly the gas may not be discharged smoothly from the vent hole 101.
In order to address this problem, Japanese Unexamined Patent Application Publication No. 1994-262993 proposes a technology wherein a escaping portion for the gas discharged from the vent hole is provided at a position on the inner wall of the vehicle which corresponds to the vent hole when the airbag is inflated.
When a conventional side airbag apparatus with a vent hole 101 on the lateral side to the vehicle body is installed in a vehicle that has a relatively low clearance, the vent hole 101 is highly likely to be blocked by a door trim 102, resulting in a failure in gas discharging since, the seat position of the vehicle is low and the window shoulder position thereof is relatively high, as shown in FIG. 7.
In order to discharge the gas without the vent hole being blocked by the door trim, there are following five options and the like for the vent hole location in the airbag: occupant side, upper end, inside of the seat, lower end, and front end. However, all of them have a problem.
(1) Vent Hole on the Occupant Side
It is difficult to discharge the gas away from the occupant.
(2) Vent Hole at the Upper End of the Airbag
When a curtain airbag is provided, the curtain air bag blocks the vent hole.
(3) Vent Hole Inside the Seat
A seat material may be subject to heat damage.
Furthermore, since the vent hole is located close to a gas inlet, the gas is promptly discharged and sufficient protection performance cannot be ensured.
(4) Vent Hole at the Lower End of the Airbag
The vent hole may be blocked by a seat cushion.
Furthermore, gas around the lower back of the occupant is promptly discharged and sufficient protection performance cannot be ensured.
(5) Vent Hole at the Front End of the Airbag
Since the vent hole is located close to an arm of the occupant, the possibility cannot be eliminated that the arm may block the vent hole and the gas hit the arm.